Trying to revive Hymn library for Hylang 0.27

[wrobell]

I am trying to adapt Hymn library code to Hylang 0.27. And I seem to be way over my head here...

This is what I have at the moment: https://github.com/pyx/hymn/compare/master...wrobell:hymn:hy-0.27?expand=1.

I have changed Maybe monad example to

(import
  hy.pyops [/]
  hymn.types.maybe [Just Nothing maybe])

(require hymn.macros [do-monad-return])

(do-monad-return [a (Just 1) b (Just 1)] (/ a b))
(do-monad-return [a Nothing b (Just 1)] (/ a b))
(setv safe-div (maybe /))
(safe-div 42 42)
(safe-div 42 'answer)
(safe-div 42 0)

The error I am getting is

$ hy hymn-maybe.hy
Traceback (most recent call last):
  File "/home/wrobell/.local/bin/hy", line 8, in <module>
    sys.exit(hy_main())
             ^^^^^^^^^
  File "<frozen runpy>", line 291, in run_path
  File "<frozen runpy>", line 98, in _run_module_code
  File "<frozen runpy>", line 88, in _run_code
  File "/home/wrobell/projects/hymn/hymn-maybe.hy", line 1, in <module>
    (import

  File "/home/wrobell/projects/hymn/hymn/types/monad.hy", line 26, in __rshift__
    (defn __rshift__ [self f] (.bind self f))
                               ^^^^^^^^^^^^^
  File "/home/wrobell/projects/hymn/hymn/types/maybe.hy", line 47, in bind
    (if self (f self.value) Nothing))
              ^^^^^^^^^^^^^
TypeError: _hy_anon_var_2() missing 1 required positional argument: 'hyx_XampersandXoptional'

Any suggestions how I could debug this? (I am accepting fish as well ;))

[Kodiologist]

That error means a function uses the old &optional style for declaring optional arguments. The style required by more recent versions of Hy looks like (fn [[argument-name default-value]] …).

[wrobell]

With the following commit, I have managed to make the Maybe monad work: pyx/hymn@5a25016